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- Page navigation anchor for A call to reconsider the new diagnostic criteria for Gestational Diabetes MellitusA call to reconsider the new diagnostic criteria for Gestational Diabetes Mellitus
We read the report by Nethery and colleagues with great interest, having noted a similar dramatic increase in GDM incidence in Australia coincident with widespread adoption of the 1-step test using the IADPSG criteria. Although the authors of the current report did not examine clinical or health system impacts from the change in diagnostic practice in their study, they note that “Health system costs may increase, with a need for more endocrinologists, diabetes nurse educators or dietitians; additional sonograms; or more intensive monitoring during labour, delivery and the postpartum period.”
Convincing evidence from a number of large RCTs now shows that, despite the new diagnostic processes detecting more disease, the clinical outcomes for the mother and baby may not be improved(1-3) and there may be net harm. Possible harms from the widened definition of GDM, not mentioned in the current report, include: life disruptions and psychosocial burdens for the women diagnosed and their families, more invasive forms of delivery of the baby, and potential harms to the infant from restricted diets and the use of insulin, including an increased risk of the infant being small for gestational age and neonatal hypoglycaemia.
The 1-step test using IADPSG criteria has resulted in three related changes in diagnostic practice: (i) use of 1 step instead of 2 step testing, (ii) lowered diagnostic thresholds, and (iii) the requirement of only 1 abnormal test out of multiple tes...
Show MoreCompeting Interests: The authors are part of Wiser Healthcare, an Australian-based research collaboration for reducing overdiagnosis and overtreatment: https://www.wiserhealthcare.org.auReferences
- 1. Pillay J, Donovan L, Guitard S, Zakher B, Gates M, Gates A, et al. Screening for Gestational Diabetes: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2021;326(6):539-62.
- 2. Brady M, Hensel DM, Paul R, Doering MM, Kelly JC, Frolova AI, et al. One-Step Compared With Two-Step Gestational Diabetes Screening and Pregnancy Outcomes: A Systematic Review and Meta-analysis. Obstet Gynecol. 2022;140(5):712-23.
- 3. Crowther CA, Samuel D, McCowan LME, Edlin R, Tran T, McKinlay CJ. Lower versus Higher Glycemic Criteria for Diagnosis of Gestational Diabetes. New England Journal of Medicine. 2022;387(7):587-98
- 4. Doust JA, Bell KJL, Glasziou PP. Potential Consequences of Changing Disease Classifications. JAMA. 2020;323(10):921-2
- 5. Bell K, Doust J, Sanders S, Buchbinder R, Glasziou P, Irwig L, et al. A novel methodological framework was described for detecting and quantifying overdiagnosis. Journal of Clinical Epidemiology. 2022;148:146-59
- Page navigation anchor for RE: Incidence of Gestational Diabetes in BCRE: Incidence of Gestational Diabetes in BC
Question:
What criteria were used to make the diagnosis of gestational diabetes in this study?The labs in British Columbia presently universally use the “alternative” 1 step test reference ranges for the 75g 2h OGTT test , regardless of whether a “preferred” 2 step or “alternative” 1 step approach to gestational diabetes testing has been taken. I have been told there is no way for the lab to tell if the 75g OGTT ordered is part of a 1 step or 2 step approach, so the lab applies the same reference ranges to all of them.
Were the authors able to distinguish between the 75g OGTT tests that were the one step approach verses those which were the second step of a 2 step approach?
Application of the alternative 1 step reference ranges leads to a diagnosis of GDM in individuals who do not meet the CDA and SOGC criteria if they have undertaken the “preferred” 2 step tests.
For example; a pregnant individual who has a lab value of 7.9mmol/L on their 50g 1h OGTT will screen positive and be offered the second step (2h 75g OGTT test.)
If they have a fasting lab value of 5.1mmol/L in BC they will be diagnosed as having GDM. (A diagnosis of GDM is made if one plasma glucose value is abnormal (i.e. fasting ≥5.1 mmol/L, 1 hour ≥10.0 mmol/L, 2 hours ≥8.5 mmol/L).If the lab had applied the CDA guideline reference ranges (https://www.canadianjournalofdiabetes.com/article/S1...
Show MoreCompeting Interests: None declared.References
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